1. Field of the Invention
This invention relates to a drag reduction apparatus for a trailer and more particularly to a drag reduction apparatus which is secured to each of the upper side rails of the body of the trailer. Even more particularly this invention relates to a cover member which is secured to each of the upper side rails so as to extend over the recesses in the upper side rails to prevent air flow from entering the recesses.
2. Description of the Related Art
Semi-trailer bodies have a floor with a forward end, a rearward end, a left side and a right side. A front wall extends upwardly from the forward end of the floor, a left wall extends upwardly from the left side of the floor, and a right wall extends upwardly from the right side of the floor. A rear wall including door supporting structure is provided at the rearward end of the floor for supporting one or more doors therein. An elongated left upper side rail is secured to the upper end of the left wall and an elongated right upper side rail is secured to the upper end of the right wall. A forward upper rail is secured to the upper end of the front wall. In some semi-trailer bodies, a rearward upper rail is secured to the upper end of the rear wall. In some cases, curved rail portions join the front ends of the upper side rails to the outer ends of the front upper rail. In some cases, curved rail portions join the rear ends of the upper side rails to the outer ends of the rear upper rail. A roof is secured to the upper rails and extends therebetween.
In many trailers, the upper side rails have a recess portion formed therein at the outer side thereof. Air flow impinging in the recessed portions of the upper rails will create an aerodynamic drag which will have an impact on the fuel consumption of the truck pulling the trailer. The recessed portion in the front upper rail does not pose any appreciable aerodynamic drag since drag reduction devices are commonly mounted on the roof of the truck to cause the airflow to pass upwardly over the front upper rail. However, in some cases, the drag reduction devices on the cab roof do not prevent air flow from impinging into the recessed portion of the front upper rail. Further, since most trucks and trailers are subjected to cross winds, air flow will be impinged into the side upper rails into the recessed areas thereby creating an aerodynamic drag having an impact on the fuel consumption of the truck.